Critics of Google's bid have pointed out that the model has very low barriers to entry, with hundreds of competitors. But it's worth pointing out that LivingSocial is the only competitor that has reached a scale remotely close to Groupon's. An industry source estimates that the next nearest competitors -- Tippr and BuyWithMe -- are probably about a tenth the size of LivingSocial.

Disclosure: Jeff Bezos is an investor in Business Insider through his personal investment company Bezos Expeditions.